/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

struct MD5Generator
{
    void processBlock (const void* data, size_t dataSize) noexcept
    {
        auto bufferPos = ((count[0] >> 3) & 0x3f);

        count[0] += (uint32_t) (dataSize << 3);

        if (count[0] < ((uint32_t) dataSize << 3))
            count[1]++;

        count[1] += (uint32_t) (dataSize >> 29);

        auto spaceLeft = (size_t) 64 - (size_t) bufferPos;
        size_t i = 0;

        if (dataSize >= spaceLeft)
        {
            memcpy (buffer + bufferPos, data, spaceLeft);
            transform (buffer);

            for (i = spaceLeft; i + 64 <= dataSize; i += 64)
                transform (static_cast<const char*> (data) + i);

            bufferPos = 0;
        }

        memcpy (buffer + bufferPos, static_cast<const char*> (data) + i, dataSize - i);
    }

    void transform (const void* bufferToTransform) noexcept
    {
        auto a = state[0];
        auto b = state[1];
        auto c = state[2];
        auto d = state[3];

        uint32_t x[16];
        copyWithEndiannessConversion (x, bufferToTransform, 64);

        enum Constants
        {
            S11 = 7, S12 = 12, S13 = 17, S14 = 22, S21 = 5, S22 = 9,  S23 = 14, S24 = 20,
            S31 = 4, S32 = 11, S33 = 16, S34 = 23, S41 = 6, S42 = 10, S43 = 15, S44 = 21
        };

        FF (a, b, c, d, x[ 0], S11, 0xd76aa478);     FF (d, a, b, c, x[ 1], S12, 0xe8c7b756);
        FF (c, d, a, b, x[ 2], S13, 0x242070db);     FF (b, c, d, a, x[ 3], S14, 0xc1bdceee);
        FF (a, b, c, d, x[ 4], S11, 0xf57c0faf);     FF (d, a, b, c, x[ 5], S12, 0x4787c62a);
        FF (c, d, a, b, x[ 6], S13, 0xa8304613);     FF (b, c, d, a, x[ 7], S14, 0xfd469501);
        FF (a, b, c, d, x[ 8], S11, 0x698098d8);     FF (d, a, b, c, x[ 9], S12, 0x8b44f7af);
        FF (c, d, a, b, x[10], S13, 0xffff5bb1);     FF (b, c, d, a, x[11], S14, 0x895cd7be);
        FF (a, b, c, d, x[12], S11, 0x6b901122);     FF (d, a, b, c, x[13], S12, 0xfd987193);
        FF (c, d, a, b, x[14], S13, 0xa679438e);     FF (b, c, d, a, x[15], S14, 0x49b40821);

        GG (a, b, c, d, x[ 1], S21, 0xf61e2562);     GG (d, a, b, c, x[ 6], S22, 0xc040b340);
        GG (c, d, a, b, x[11], S23, 0x265e5a51);     GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa);
        GG (a, b, c, d, x[ 5], S21, 0xd62f105d);     GG (d, a, b, c, x[10], S22, 0x02441453);
        GG (c, d, a, b, x[15], S23, 0xd8a1e681);     GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8);
        GG (a, b, c, d, x[ 9], S21, 0x21e1cde6);     GG (d, a, b, c, x[14], S22, 0xc33707d6);
        GG (c, d, a, b, x[ 3], S23, 0xf4d50d87);     GG (b, c, d, a, x[ 8], S24, 0x455a14ed);
        GG (a, b, c, d, x[13], S21, 0xa9e3e905);     GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8);
        GG (c, d, a, b, x[ 7], S23, 0x676f02d9);     GG (b, c, d, a, x[12], S24, 0x8d2a4c8a);

        HH (a, b, c, d, x[ 5], S31, 0xfffa3942);     HH (d, a, b, c, x[ 8], S32, 0x8771f681);
        HH (c, d, a, b, x[11], S33, 0x6d9d6122);     HH (b, c, d, a, x[14], S34, 0xfde5380c);
        HH (a, b, c, d, x[ 1], S31, 0xa4beea44);     HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9);
        HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60);     HH (b, c, d, a, x[10], S34, 0xbebfbc70);
        HH (a, b, c, d, x[13], S31, 0x289b7ec6);     HH (d, a, b, c, x[ 0], S32, 0xeaa127fa);
        HH (c, d, a, b, x[ 3], S33, 0xd4ef3085);     HH (b, c, d, a, x[ 6], S34, 0x04881d05);
        HH (a, b, c, d, x[ 9], S31, 0xd9d4d039);     HH (d, a, b, c, x[12], S32, 0xe6db99e5);
        HH (c, d, a, b, x[15], S33, 0x1fa27cf8);     HH (b, c, d, a, x[ 2], S34, 0xc4ac5665);

        II (a, b, c, d, x[ 0], S41, 0xf4292244);     II (d, a, b, c, x[ 7], S42, 0x432aff97);
        II (c, d, a, b, x[14], S43, 0xab9423a7);     II (b, c, d, a, x[ 5], S44, 0xfc93a039);
        II (a, b, c, d, x[12], S41, 0x655b59c3);     II (d, a, b, c, x[ 3], S42, 0x8f0ccc92);
        II (c, d, a, b, x[10], S43, 0xffeff47d);     II (b, c, d, a, x[ 1], S44, 0x85845dd1);
        II (a, b, c, d, x[ 8], S41, 0x6fa87e4f);     II (d, a, b, c, x[15], S42, 0xfe2ce6e0);
        II (c, d, a, b, x[ 6], S43, 0xa3014314);     II (b, c, d, a, x[13], S44, 0x4e0811a1);
        II (a, b, c, d, x[ 4], S41, 0xf7537e82);     II (d, a, b, c, x[11], S42, 0xbd3af235);
        II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb);     II (b, c, d, a, x[ 9], S44, 0xeb86d391);

        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;
    }

    void finish (uint8_t* result) noexcept
    {
        uint8_t encodedLength[8];
        copyWithEndiannessConversion (encodedLength, count, 8);

        // Pad out to 56 mod 64.
        auto index = (count[0] >> 3) & 0x3f;
        auto paddingLength = (index < 56 ? 56 : 120) - index;

        uint8_t paddingBuffer[64] = { 0x80 }; // first byte is 0x80, remaining bytes are zero.

        processBlock (paddingBuffer, (size_t) paddingLength);
        processBlock (encodedLength, 8);

        copyWithEndiannessConversion (result, state, 16);
    }

private:
    uint8_t buffer[64] = {};
    uint32_t state[4] = { 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476 };
    uint32_t count[2] = {};

    static void copyWithEndiannessConversion (void* output, const void* input, size_t numBytes) noexcept
    {
       #if JUCE_LITTLE_ENDIAN
        memcpy (output, input, numBytes);
       #else
        auto dst = static_cast<uint8_t*> (output);
        auto src = static_cast<const uint8_t*> (input);

        for (size_t i = 0; i < numBytes; i += 4)
        {
            dst[i + 0] = src[i + 3];
            dst[i + 1] = src[i + 2];
            dst[i + 2] = src[i + 1];
            dst[i + 3] = src[i + 0];
        }
       #endif
    }

    static uint32_t rotateLeft (uint32_t x, uint32_t n) noexcept     { return (x << n) | (x >> (32 - n)); }

    static uint32_t F (uint32_t x, uint32_t y, uint32_t z) noexcept  { return (x & y) | (~x & z); }
    static uint32_t G (uint32_t x, uint32_t y, uint32_t z) noexcept  { return (x & z) | (y & ~z); }
    static uint32_t H (uint32_t x, uint32_t y, uint32_t z) noexcept  { return x ^ y ^ z; }
    static uint32_t I (uint32_t x, uint32_t y, uint32_t z) noexcept  { return y ^ (x | ~z); }

    static void FF (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + F (b, c, d) + x + ac, s) + b;
    }

    static void GG (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + G (b, c, d) + x + ac, s) + b;
    }

    static void HH (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + H (b, c, d) + x + ac, s) + b;
    }

    static void II (uint32_t& a, uint32_t b, uint32_t c, uint32_t d, uint32_t x, uint32_t s, uint32_t ac) noexcept
    {
        a = rotateLeft (a + I (b, c, d) + x + ac, s) + b;
    }
};

//==============================================================================
MD5::MD5() = default;
MD5::~MD5() = default;
MD5::MD5 (const MD5&) = default;
MD5& MD5::operator= (const MD5&) = default;

MD5::MD5 (const void* data, size_t numBytes) noexcept
{
    MD5Generator generator;
    generator.processBlock (data, numBytes);
    generator.finish (result);
}

MD5::MD5 (const MemoryBlock& data) noexcept : MD5 (data.getData(), data.getSize()) {}
MD5::MD5 (CharPointer_UTF8 utf8) noexcept : MD5 (utf8.getAddress(), utf8.getAddress() != nullptr ? utf8.sizeInBytes() - 1 : 0) {}

MD5 MD5::fromUTF32 (StringRef text)
{
    MD5 m;
    MD5Generator generator;

    for (auto t = text.text; t.isNotEmpty();)
    {
        auto unicodeChar = ByteOrder::swapIfBigEndian ((uint32_t) t.getAndAdvance());
        generator.processBlock (&unicodeChar, sizeof (unicodeChar));
    }

    generator.finish (m.result);
    return m;
}

MD5::MD5 (InputStream& input, int64 numBytesToRead)
{
    processStream (input, numBytesToRead);
}

MD5::MD5 (const File& file)
{
    FileInputStream fin (file);

    if (fin.openedOk())
        processStream (fin, -1);
}

void MD5::processStream (InputStream& input, int64 numBytesToRead)
{
    MD5Generator generator;

    if (numBytesToRead < 0)
        numBytesToRead = std::numeric_limits<int64>::max();

    while (numBytesToRead > 0)
    {
        uint8_t tempBuffer[512];
        auto bytesRead = input.read (tempBuffer, (int) jmin (numBytesToRead, (int64) sizeof (tempBuffer)));

        if (bytesRead <= 0)
            break;

        numBytesToRead -= bytesRead;
        generator.processBlock (tempBuffer, (size_t) bytesRead);
    }

    generator.finish (result);
}

//==============================================================================
MemoryBlock MD5::getRawChecksumData() const
{
    return MemoryBlock (result, sizeof (result));
}

String MD5::toHexString() const
{
    return String::toHexString (result, sizeof (result), 0);
}

//==============================================================================
bool MD5::operator== (const MD5& other) const noexcept   { return memcmp (result, other.result, sizeof (result)) == 0; }
bool MD5::operator!= (const MD5& other) const noexcept   { return ! operator== (other); }


//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

class MD5Tests final : public UnitTest
{
public:
    MD5Tests()
        : UnitTest ("MD5", UnitTestCategories::cryptography)
    {}

    void test (const char* input, const char* expected)
    {
        {
            MD5 hash (input, strlen (input));
            expectEquals (hash.toHexString(), String (expected));
        }

        {
            MemoryInputStream m (input, strlen (input), false);
            MD5 hash (m);
            expectEquals (hash.toHexString(), String (expected));
        }
    }

    void runTest() override
    {
        beginTest ("MD5");

        test ("", "d41d8cd98f00b204e9800998ecf8427e");
        test ("The quick brown fox jumps over the lazy dog",  "9e107d9d372bb6826bd81d3542a419d6");
        test ("The quick brown fox jumps over the lazy dog.", "e4d909c290d0fb1ca068ffaddf22cbd0");

        expectEquals (MD5 (CharPointer_UTF8 (nullptr)).toHexString(), String ("d41d8cd98f00b204e9800998ecf8427e"));
    }
};

static MD5Tests MD5UnitTests;

#endif

} // namespace juce
